Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description does add real behavioral context: credit costs, zero cost for empty/error results, and cache reuse semantics with a cached_at marker. However, it is self-contradictory about cost ('1 credit per request' vs 'at least 10 Nexscope credits') and specifies no rate limits or retry behavior, so an agent cannot reliably predict the charge.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The core paragraph is pasted twice in full, and the text closes with scraped marketing fragments ('Reddit Post Transcript API View Pricing Get the transcript from a Reddit video post 1 credit per request') that read as page clutter rather than specification. The genuinely useful facts are buried mid-paragraph rather than front-loaded, and the duplication makes the definition roughly twice as long as needed.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a read-only fetch tool with no output schema, the definition covers the essentials an agent needs: accepted URL forms, the null/transcriptNotAvailable failure shape, named return fields (raw_vtt, transcript), caching behavior, and cost implications. The gaps are the undocumented interaction of the 'language' parameter with the caption-only behavior and the unresolved cost figures.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so all three parameters are already documented, including the cache_max_age enum and its credit implications. The description's parameter content largely restates the schema verbatim and it never mentions the 'language' parameter, so it adds little meaning beyond structured fields — the baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb and resource ('Gets the transcript from a Reddit video post or direct v.redd.it URL') and adds the crucial precondition that Reddit must expose a VTT caption file. That precondition distinguishes it from social_reddit_post_detail, but no sibling is named explicitly, so an agent must infer the routing itself.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It gives clear when-it-works and when-it-fails conditions ('If Reddit does not expose captions for the video, transcript is null and transcriptNotAvailable is true') and clarifies that no AI transcription is involved, which rules out expecting generated captions. It never names an alternative tool for non-video Reddit posts or for videos without captions, so the 'use X instead' half of the guidance is missing.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.